


If You Want Blood (You've Got It)

by twobettafish



Category: Marvel Cinematic Universe
Genre: Blood, Blood Drinking, Gratuitously Convenient Ship-Friendly Situations, I said vampires, Look out for any warnings you might associate with the topic related to blood violence etc., M/M, Self-Harm, Vampires, Violence, you read that right
Language: English
Status: Completed
Published: 2018-11-26
Updated: 2018-12-07
Packaged: 2019-08-29 14:24:17
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 6
Words: 19,230
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/16745677
Author URL: https://archiveofourown.org/users/twobettafish/pseuds/twobettafish
Summary: Mystical threats always need to be dealt with, even if doing so requires Tony Stark's help.(Sometimes, though, those threats can be kind of stupid.)





	1. Chapter 1

**Author's Note:**

> I didn't have my notes with me for my giant, lengthy, complicated story when I did some Thanksgiving traveling, so I whipped out something else on the road!
> 
> It is not lengthy. It handwaves a lot of canon. It's downright silly, a lot of times. And it involves vampires.
> 
>  
> 
> _Buckle up, 'cause things are about to get real dumb._

"I should be back in a few days," Wong said as he hefted his bag and raised the hand that bore a sling ring.

"A few?" echoed Stephen. "How imprecise." 

With a flat look, Wong lowered his hand back to his side. "You're thinking of the fissures from Kartoth, aren't you?"

Five days earlier, Stephen had the local news playing in the background while he worked. It was fortunate that he'd glanced up from a book when he had, for the reporter talking about the upcoming Shakespeare in the Park production didn't seem to notice the cracks in reality appearing around her. Nor did the anchors back in the studio.

Stephen had promised Wong that only 'a few' fissures were there as he announced his solo departure. It had seemed like a standard patch job: identify the forces pressing on their dimension, understand the forces they wielded, and bolster the walls accordingly. Simple. He handled that sort of thing on a weekly basis.

And if not for the demons actively trying to claw their way into Central Park, it would have been a standard job. But there were in fact demons, and those demons brought friends who also brought friends, and Stephen was barely able to push them all back into their home dimension of Kartoth before they began possessing the Titus Andronicus audience. 

Wong had brought up Stephen's sketchy mission plan in occasional jabs since then. When Wong used the same wording, Stephen couldn't help but prod at it. "Maybe. And I am in fact surprised that you don't know the precise minute you'll return from your librarian party."

"Conclave." Wong raised his hand again. "We begin with a general meeting, but that progresses into retrieval. The timeline is flexible."

"Ah. Well, I hope you and the books have fun."

"I hope you don't," Wong replied with a faint smirk.

"I am the master of this Sanctum, you know," Stephen pointed out with one arched eyebrow. While Wong had more formal training, after his uses of the Time Stone Stephen did have hands-on experience that no one else would (hopefully) ever be able to claim. "And I'm good."

"You're also you, Stephen," Wong chuckled as his portal opened, then insisted, "Don't have too much fun."

"With you gone," Stephen announced as the portal closed, "fun'll actually be a lot easier."

He had the place to himself, then. "I'm planning a kegger right now," he announced as he walked down the stairs into the main entrance hall, just in case Wong was still listening in. "Free entry to everyone taking summer classes." After waiting a few seconds, he nodded. Good. He seemed to be genuinely alone.

_Want anything?_ he soon typed into his phone, and waited to see if he'd get a response or if Christine was busy with surgery.

_God yes_ came the nearly immediate reply. _Family got sideswiped by a garbage truck._ Well, she didn't sound like she'd had a very fun day.

_brb_

It was fortunate that he'd moved so quickly; it was evening in San Sebastián and the restaurant he'd earlier discovered didn't stay open late. A bag full of pintxo skewers and slices of pastel Vasco cake were soon his, and he stepped back across the Atlantic into the hospital storage room they'd started treating as his landing pad.

"God, thank you," Christine said as she walked into the room, smelled the food he was carrying, and stole the entire bag of skewers to start devouring whatever she could grab. "Ten hours," she explained between bites. That sounded about right for handling the trauma caused by a truck-versus-family. Once the worst of her hunger had eased, she offered him the bag again.

With a lopsided smile, Stephen took it and began his own meal. "How'd the family do?"

"Ugh." Well, that summed it unfortunately up. "This is good," Christine said as she nibbled more politely at another of the skewers. "I was actually expecting Italian. I know that's my go-to."

"Yeah, well, I figured I'd avoid tomatoes after surgery gone bad."

"What?" A second later, as she presumably imagined her traditional bolognese order with its red sauce and roughly ground meat, her nose wrinkled. "Oh. Gross. Thanks. I guess I'm done ever eating Italian, now."

"Sorry." He extended one of the small boxed slices from the other bag. "There's cake."

"Well. I can probably handle that," Christine said after putting on a show of consideration and took it from him. "Thanks. You do the best UberEats delivery ever, you know."

"I'm truly living up to my potential," Stephen said wryly. "But seriously, now that I saved the Shakespeare audience from getting collectively targeted by demons—" He cut off to sigh at her expression. "Will you stop making that face? Would it help if I called them energy-fueled apex predators from a parallel dimension?"

Christine paused to consider that. "A little bit, actually. It makes me feel less like you're telling me that I need to look out for werewolves, vampires, and zombies."

"Lycanthropy is apparently exceedingly rare, I wouldn't worry. As for the oth... not the point, never mind. Titus Andronicus is getting good reviews and I wouldn't mind double-checking my work with those dimensional walls. Want to take your mind off things?" Tickets were normally hard to come by, but he'd saved their entire production from being demon food. Using magic to score a pair hardly counted as cheating. 

"Isn't that play incredibly depressing?"

Stephen shrugged. "Well, I figured you'd have a beer or three."

She thought about it for another second longer, then shrugged back. "Sure, why not."

Their romantic relationship years back had withered on the vine, and the platonic one after that had blown up spectacularly. (Courtesy of him.) Now that Stephen was back with fresh purpose and a fresh outlook, they'd discovered that they could actually form an excellent friendship. 

For one, his competitive qualities were lessened by them not working in the same sphere.

In his new life, it was other people who'd fire those instincts up, instead.

"Why is he here?" Stephen grumbled as they approached the audience seating. Though most people streamed toward the seats surrounded by the summer greenery of Central Park, someone else was making a beeline straight toward him: Tony Stark. 

After the mess with Thanos had resolved, Tony had decided to step back from serving in any sort of official heroic role. The nightmare hanging over him had lifted and there were others to handle new threats, now. That was the story that everyone was told: Iron Man was no more and Tony Stark was only contributing to the world with his inventor's brain.

Everyone, however, did not live in New York City.

Tony's "official hero retirement" apparently gave him plenty of wiggle room to pause his inventing work and check in on the active area heroes. And while Parker was always happy to see him, Tony's offices were in Manhattan, not Queens. He didn't even need to cross a bridge to bother Stephen. "Is something going down?" Tony wondered as he walked up. "My sensors read your portal."

"What? We arrived over at the edge of the park." 

"Right, I'm tracking you all over the city so I can anticipate any hostiles you might be following." Seeming to realize he'd interrupted something, Tony pointed to Stephen's side. "Christine, right?"

"Mmm hmm. And we're here to watch the show."

"You're tracking my movement all over the city?" Stephen repeated in disbelief. "Absolutely not. Stop that right now, Stark."

"I'm just trying to—"

"You retired."

"From this," Tony retorted and rebounded his fingertips off his sternum. There was no nano housing unit, arc reactor, or anything of the sort there. He had yet to give in and re-install something that would power a suit, though Stephen was halfway sure it'd eventually happen. "Just because I left behind my suit doesn't mean that I don't care what happens to people. If I see you portaling over to fight something in the Financial District, maybe I can call for an evac before things go full Twilight Zone."

"You really have been watching me." The Financial District had been two weeks earlier. Someone tried to turn the golden bull of Wall Street into an actual idol that affected the minds of people walking by. "Stop."

"I'm trying to help."

"I don't need your help! I—" Frowning, Stephen looked down as something cold was pressed into his hand. Tony did the same.

Christine lifted her own beer bottle, then gestured with it to the bottles she'd handed to both men. "We should probably take our seats. They look nearly ready to start."

"We're talking later," Tony insisted as he turned toward the area for charitable sponsors. That explained his attendance, at least.

"I still can't believe you know him," Christine noted as they joined the rest of the audience. "That's kind of weirder than the magic."

Stephen rolled his eyes but bit back on any easy replies. Though 'annoying' was basically Tony's default state, their relationship was more complicated than most people understood. Unfortunately for Stephen, Tony was one of those people. Like most of the Avengers, Tony knew that absolute tragedy had struck and remembered its broad strokes. The world in general didn't even know that much, which was why society continued on instead of collapsing into post-apocalyptic death cults.

There was only one person who remembered absolutely everything in full color, surround-sound intensity. Stephen's extensive memories included the absolute betrayal Tony had expressed when the Time Stone went to Thanos, and the breakdown he'd tipped toward when Thanos' temporary victory rippled through their bodies. It also included earlier things, like how Tony thought he was making a suicide play to go after a guy he'd known for twenty minutes. It included later things, like years of impossibly hard work done in service of the only way to win.

Because of all of that, Stephen could be annoyed at Tony and he could set boundaries, but he couldn't write the man off.

"He's a good guy," Stephen allowed, "but thanks for running interference."

"You said you wanted to check something?" Christine murmured as spotlights appeared on the stage. It was still light out, but dusk would soon fall.

"At intermission," he murmured back. He didn't see any dimensional cracks in the area, but he might be able to feel them. He'd prefer to make those gestures under some cover of darkness.

Oh, damn, he thought about ninety minutes later, outside of the main stage area and hidden behind a service building. Yes, there were new cracks. These nightly crowds were clearly too tempting. This little bit of Central Park seemed particularly close to Kartoth, as well, like the overlapping slivers of a Venn diagram. _Keep watching_ , Stephen typed to Christine as he eyed what looked like empty air but was actually more like a dimensional mosaic. _I might need to stay here until the audience leaves_

_Is everything okay??_

_No. But under control. Act normal_

Damn, he thought again as he found one of the invisible fractures and slowly began to stitch the walls back together. The play's cast had been tremendous in the first acts. No one would leave that audience by choice, but here he was, half-hidden behind a tree as he—

"What's up?"

After closing his eyes and taking a deep breath, Stephen turned to Tony. "Why are you here?"

"Something is wrong. I need to know what it is."

"Are you... wait, are you reading my text messages, too?!"

"No, no," Tony assured him. "I glanced over to where you were sitting, and Christine looked worried and you weren't there..." He stepped forward and felt uselessly at the air before resorting to the 'smart watch' on his wrist that was actually a hyper-advanced scanning device. "I'm not sure what I'm looking at. It's all a little fuzzy."

"Because this is not your territory. Leave."

"Manhattan's my territory."

"You supposedly retired, and even with the suit on you'd be useless here. Leave." As Tony began to raise protest, Stephen slammed his hand against an energy crevice that he could now see threatened to open wide. "Go back to your seat, Tony. There's nothing you can do here except distract me."

"I know you think you're a big shot in the hero biz, but let me remind you that I do have a _little_ more experience with—"

Sudden dark energy surged, threatening to burst their world's walls apart like a weakened dam. Hissing with pain, Stephen held it back with the one arm. The other gestured at Tony.

There, he thought with satisfaction as he watched the shower of sparks vanish. Now that Tony was gone, he could focus. With both arms he held back the energy of Kartoth as it sought entry. "I'm going to need to re-align this whole part of Central Park," he muttered as warmth flowed out of his arms and into that other dimension. "We can't keep doing this."

God, there must be a lot of them behind this wall. They'd been prepared to feed on an entire audience, and even though Stephen was shielded the sheer number of demons was starting to wear on his defenses. Ignoring his phone as it buzzed, Stephen focused instead on how the chill of their energy absorption had extended up through his shoulders. It'd probably be a bad idea to let it hit his head.

For a fraction of a second, his shields dropped. The demons were so startled by the sudden change that most of them flinched away, anticipating some change in strategy. They were right. Like pulling back a fist to wind up for a stronger punch, Stephen's energy blow flooded through the dimensional cracks and adhered to the other side like a messy welding job. There. That should keep things sealed until Wong returned and they located a more permanent solution, at least.

Now, he just needed to—

The world tilted as he turned back toward the stage. They really had drained him, Stephen thought and leaned against a nearby tree. After a short bout of shivering despite the warm, humid evening, two fingers checked his carotid artery. He shook his head slowly, careful to not prompt another bout of dizziness. Damn. His pulse was slow. Clearly these demons did feed on life energy. Thank God he'd decided to come back to the park tonight, or the entire audience would have been left as husks.

_What the hell was that????????????????????_ demanded a notification on his phone's lock screen. Stephen ignored Tony's outrage and clicked into his messages with Christine. If she'd picked up anything salty at intermission, he could use a boost to his blood pressure while things steadied out over the next day or two.

"You okay?" she murmured as he slid back into his seat. On his prompting, they'd taken seats right near an exit. The usher still shot him a disapproving look.

"Dizzy," he admitted in a whisper. "But it's done."

She pressed her fingers against Stephen's neck, frowned at the slow pulse, and handed over the pretzel bites that had appeared during his absence. "Do we need to head out?"

"No, not at all." It actually felt good to be surrounded by all these lives he'd saved. They could stay here while his system steadied. "And I'll just stick to water," he added after noticing the beer bottle at her side. 

"All right," she whispered uncertainly. She'd probably check his pulse again before they left. "I guess we can..." Trailing off as her cell phone began to buzz, Christine frowned at her notification screen where an unknown number was blowing up her messages. "You apparently sent Tony somewhere?"

"Remember that Four Seasons for the emergency neuroimaging conference?"

Christine paused. "The one in Miami?" Her whisper became more of a hiss. "Oh my God, you can't just send people around the world, Stephen."

"It's only a thousand miles or so, and he—" Didn't have his suit any more. Oh. Right. Okay, he probably should have picked somewhere closer to deposit Tony. "He has private jets everywhere," Stephen awkwardly finished. Oh, he was gonna hear about this one tomorrow.

"I can't believe you know him," Christine insisted in a whisper as she sat back against her seat. 

After however long it took to get a plane arranged and fly back to New York, Stephen was going to get far more than an earful from Tony Stark. He should probably ignore that imminent return and the lingering chill in his body, and instead focus on the play. For right now, things could be fun. He knew they'd soon get worse.


	2. Chapter 2

"Should we take an Uber or something?" Christine asked after the end of the play, when they'd walked away from the audience to find a small, tree-shielded curve of the park's path. 

Stephen slid on his ring. "No, it's fine. We took some turns away from everyone else. Not many people will notice the portal and it'd be gone by the time anyone came to check."

"That's not what I meant. You were really dizzy earlier."

"It's mostly resolved." He raised his hand, only to drop it with an annoyed noise when two of Christine's fingers checked his pulse yet again. "Do you mind?"

"It's still slow and you still feel a little chilled."

"They're energy harvesters, so obviously. It'll take me a night or two to regenerate what life force they took." Off her expression, Stephen shrugged and asked, "What?"

"Energy harvesters? Life forces?"

"Yes, energy harvesters," Stephen patiently repeated. "And life forces. And I know Tony Stark. And I don't need an Uber." He said the last bit as a portal opened. 

In the Sanctum's entry hall, Christine looked distantly contemplative as the portal spun away into nothing. After gnawing on her lip she asked with great hesitation, "Have you even been in a car... since...?"

"A car wouldn't bring you take-out from Spain," Stephen retorted and thought of the leftovers sitting in his fridge. Hopefully they kept well until tomorrow. 

She said nothing for a few seconds, then asked, "Do you want to stay at my place tonight? On the couch," she instantly added when his eyebrows began to rise. "I'm sorry, I'm just not used to 'life force energy harvesting.' I don't know how to diagnose this."

"Your professional recommendation should be 'go to sleep in your own bed, Stephen, which is much more comfortable than a couch.'" With a wry smile, he added, "And I should probably get what sleep I can before Tony gets back and starts yelling at me. I'm sure he's well on his way." He'd silenced his phone after it kept buzzing. It had buzzed an awful lot.

"Call me if you feel any worse," Christine relented after a moment, then dug out her phone.

"I'm fine. Now, let me—" His arm dropped before he could put the sling ring to another use, for Christine flipped around her phone to show him an Uber pickup request. "You know, portals require essentially no effort on my part."

"Get some sleep before Tony yells at you," Christine laughed as she headed for the door, "and thanks for the food."

"Fine," he said to no one in particular after the door closed. With a gesture, the glamour spell he'd used fell away and the Cloak of Levitation re-appeared. He hadn't wanted to leave it behind in case there was a crisis, but it didn't exactly go with a casual outfit. "I clearly patched that dimensional wall well enough until Wong gets back to help with a full restoration, right? Right."

The Cloak seemed to agree. (He assumed.)

"Anyway, I'm not letting Tony in until I get a good night's sleep. Please keep an eye out for him trying to get inside somehow."

As the Cloak lifted away from him and bobbed its collar, Stephen began to walk up the stairs only to turn and ask, "It was a good show, wasn't it? Not that I expect you to be a critic, but—" 

That wasn't a smart move to make, he realized a second later. He was still a little slow and a staircase wasn't the best place to stop and turn. After the fresh daze passed, he changed his speech to, "Right. Thanks. Don't let him in."

At least sleep came easily. Any dizziness was mostly gone when Stephen woke, but to his consternation his pulse was still slow. His skin no longer felt chilled when he touched it, but the thermometer flashed at 96.1 degrees. Flipping it to Celsius gave the same result: he was just outside of a normal temperature range. "Odd that I'm not shivering," he mused as he returned to his bedroom and instinctively reached for his phone.

That was good timing. He hadn't un-silenced it, so it didn't buzz with the alert of an incoming text, but a notification still flashed that he otherwise wouldn't have noticed: _STRANGE YOU HAVE EXACTLY FIVE MINUTES BEFORE I FIGURE OUT A WAY INSIDE_.

"Hi, yeah, sorry," he said into his phone as he headed downstairs. "You're outside right now? Good."

"Good?" Tony repeated in disbelief as he abruptly appeared at the base of the Sanctum's main stairway. It took him a second to realize that he was now inside the building, and with a blank stare he tapped his watch and ended their call. "Okay, then."

As Stephen slid his phone into his pocket and proceeded down the stairs, he continued, "In my defense, I forgot that you didn't have your suit to fly back."

"'I forgot' is not a defense, and—" Tony spread his hands before demanding, "Miami?"

He shrugged. "I liked that hotel." Tony's expression was still dark and so Stephen explained, "You got in my way and were about to make a bad situation worse. I had to make a snap call."

"You portaled me to _Miami_ and I had to explain to all those people at the pool why I suddenly appeared there," Tony seethed. "And that appearing like that did not mean I was back in the hero business."

The pool? Why had he picked the pool? Oh, right, their outdoor lounge had great ceviche. "There were enough demons to feed on the vitality of the entire audience. Since you were standing next to me, every single one of them would have plowed straight through you to kick things off." Stephen began walking and gestured for Tony to follow. Though it seemed to annoy Tony, he did as requested. "You want coffee?"

"I... sure. Black, a little sugar." Disgruntlement ebbed slightly as Tony wondered, "So, the audience was okay?"

"The audience was okay," Stephen confirmed as he reached for the coffee pot that had auto-brewed to greet him. It smelled faintly odd, though it was the same roast as always, and Tony said nothing as he accepted his mug. Ugh, it tasted a bit muddy, too. He'd have to complain about whatever batch the store had bagged for him. 

Stephen settled at the table and continued, "I held the wall closed while they were trying to come through, then did a heavy-duty patch job. It'll hold until Wong returns and we can re-align Central Park out of convergence with Kartoth." 

"You're going to 're-align' part of the city?" Tony repeated dubiously. After another sip he added, "Good coffee, by the way."

Stephen frowned at that, then ignored their drinks to answer, "Not a physical re-alignment, don't worry."

Tony frowned, too. "How exactly does that work?"

"Basically, Kartoth currently has an exceptional view of Central Park. I plan to fog up their lenses. That'll make reaching into our dimension a less appealing prospect. In the meantime people are ripe targets for having their lives drained, but I stopped that attempt last night." Stephen lifted his mug of coffee like he was toasting Tony. "And so you can go back to your clean energy development projects." _And get out of my way._

"People's lives are actually getting drained?" Tony repeated.

"No, because I fixed things. No demons got through before I sealed the wall." Stephen took another sip of coffee. Even if the taste was off, the warmth still felt nice. "Though you tried to distract me, I held them all back literally bare-handed."

Tony studied him. "They drained you while you held them back, didn't they?"

"Excuse me?"

"You look a little off."

"Ex _cuse_ me?"

"Fine," Tony said after a moment of tapping his fingers against the table in thought. "I may not be able to sense dimensional walls, but I can scan for energy. I'll set something up to monitor Central Park and let you know if I see any warning signs." As Stephen opened his mouth to protest, Tony added, "You owe me for Miami, Strange. I'm scanning Central Park and there's nothing you can do about it."

"Fine."

Tony folded his arms and echoed, "Fine."

Stephen folded his arms, too. "Fine."

"I'm gonna go do that now."

"I'll be sure not to portal you there."

"Well," Stephen announced to the Cloak once they were left blessedly alone, "that wasn't the best way to start my day." He opened the fridge, but frowned when its interior smelled as odd as the coffee had. Those skewer leftovers were supposed to be a protein-heavy breakfast to help his recovery. 

"It'll still work," he decided a moment later and reached for the bag. The coffee had tasted off to him, but Tony thought it was normal. As little as he liked to admit that Tony might be right, he _had_ been drained by those demons. This was probably a side effect of getting assaulted by creatures who didn't eat at restaurants.

Invaded, he repeated to himself as he chewed his unappetizing breakfast. He'd known that they were draining life energy out through his limbs, but he'd also dropped his shields momentarily while he prepared for his major attack. It'd been an acceptable risk. His gambit had paid off as the demons flinched away. Had all of them pulled back, though?

_You look a little off_ floated back up from memory and Stephen sighed as he recalled Tony's words. Hell. He'd better not be possessed. That was always annoying.

"I look fine," he decided a few minutes later as he studied himself in a bathroom mirror. The room had the brightest illumination in the place. Thanks to that he could see that yes, he looked faintly pale, but that was normal after having his life force drained. It'd resolve within days. Oh, wait, he mused as he leaned in closer. His eyes were a brighter, greener shade than usual. Odd.

Well then, he had a research agenda. He needed to understand the dimension of Kartoth, discover how to un-align it with Central Park, and find out what sort of creature from that realm might be leaving him slightly chilly and with leaf-green eyes.

"Okay," he concluded hours later, when he opened the fridge to make a quick sandwich but recoiled from the scents inside. "Time for a change in plans." Food didn't just smell odd, now; it revolted him. Perhaps his own condition needed to take higher priority. Saving the city would become progressively more difficult as his stomach distracted him.

"Can you look for any books that might deal with the inhabitants of Kartoth and similar dimensions?" he asked the Cloak as he settled back at his table. Only a glass of water came with him. "I'll need anything on incorporeal creatures that feed on physical beings' life energy," he clarified, and the Cloak nodded and flew off toward the various book niches they had scattered through the Sanctum.

"Seriously?" Stephen murmured when he took his temperature again an hour later. The readings were just above thirty-two Celsius and swapping to Fahrenheit showed an identically cold result. Going by this, he was clearly hypothermic and should be getting drowsy, and yet he felt increasingly antsy. _You could ask Christine_ a voice told him, but he immediately disregarded the idea. She would try typical medical interventions and they'd obviously be useless.

The damndest thing was how he couldn't pinpoint what was wrong. He was normally so in tune with his body's natural energy, yet whatever was happening to him had all these clear symptoms but a masked cause. It felt like the source of his problems was something that knew how to hide itself. Unsettling.

A knock echoed through the Sanctum. Turning away from the medicine cabinet, Stephen closed his eyes and got the information he wanted: the person on the front steps was Tony. With a gesture, he again brought Tony inside the front hall and exited the bathroom to join him.

"That is so disorienting," Tony informed Stephen as he saw him approach. Sunglasses still covered his face and he was in a t-shirt and jeans, but had probably come straight from his office. "And... okay, you officially look like hell."

Stephen groaned and pinched the bridge of his nose as he walked slowly down the stairs. "I assume you have something to tell me?"

"A distributed network of scanners is scattered across the park. I've figured out what background noise to ignore, and so they've been able to pick up on a low-level buzz of energy that doesn't belong on Earth. It's holding steady, FYI. I'll keep an eye for any changes."

"Good." Stephen sighed, let his hand drop, and regretfully raised his gaze toward Tony's glasses. "If you know what energy to scan for, could you scan me?"

"Oh." Tony's head tilted. "Interesting. Do you actually need my help?"

"Stark."

"Fine, fine." Tony raised his watch and began scanning him, but soon stopped. 'Startled' didn't begin to describe his expression as he yanked off his sunglasses.

"Dammit, I'm possessed," Stephen instantly concluded. "What a pain in the ass. I guess only one of those things needed to sneak in while I was readying my attack."

"You're just calling this 'a pain in the ass?'" Tony asked dubiously. The scanner results on his wrist appeared to worry him more than they did Stephen. "Some sort of seriously freaky energy is all over you, and... wait, these vitals..." Before Stephen could stop him, Tony reached out and felt his forehead. "God!"

Stephen shoved his hand away, then tried feeling the skin himself. It felt normal to his own touch, though he knew from his thermometer that it clearly wasn't. "Yeah, I'm a little cold."

"A little cold?" Tony repeated in disbelief. "Antarctica's a little cold!"

"Okay, it's not that bad."

"You feel half dead!"

"I do not, I feel hypothermic."

"And what is with your eyes?" Tony demanded as he leaned in closer. "They did not look like that this morning."

His eyes? Well, they'd been an odd shade of green right after breakfast, but he hadn't paid attention to them since then. Taking his temperature again had only involved retrieving the thermometer from the medicine cabinet. With a wary look, Stephen turned from Tony and walked over to a convenient side hallway and the antique mirror it held.

Even in the dim light, it was easy to tell that his eyes had changed. They hadn't actually been turning clear green, earlier. Or rather, that crisp shade was only an intermediary step before mutating into an inhuman gold. The effect was more clear by the second. "What in the hell," Stephen murmured as he leaned closer to study the change.

As he did, his reflection blurred. Startled, Stephen pulled back a few steps and then grabbed for his phone. The screen revealed him still looking the same, so it wasn't that his body was fading toward incorporeality. Why did the mirror react that way, then, and not a phone camera?

Why, Stephen corrected as he really considered what he'd been looking at, did this antique mirror with genuine _silver_ backing barely reflect him as his eyes turned gold? As his pulse slowed and body temperature dropped, and he became progressively incapable of consuming human food? After he'd been possessed by a demon who wanted to feed on life itself? 

He had a suspicion. He had a very unfortunate suspicion.

Stephen's mood further sank as his reflection continued to blur toward vague nothingness, and plummeted even more when he heard Tony's footsteps behind him... and Tony's heartbeat. He should not be able to hear Tony's heartbeat. Dammit.

"You okay?" Tony wondered.

Sighing, Stephen turned. Even with this distance between them, he was aware of the steady thrum of Tony's heart as it forced blood through his veins. With great resignation as he accepted exactly what sort of demon had possessed him, Stephen sighed even more deeply and summarized, "Fuck."


	3. Chapter 3

"Fuck?" Tony echoed. "Well, that doesn't sound good."

"Look at the mirror," Stephen said grimly.

"The mirror? What about the..." Tony trailed off as he took in the sight there: Stephen's reflection, faded into little more than a blur of colors. "Please tell me that's a funhouse prop." He leaned in, checked his own crisp reflection, and grimaced. "Apparently not."

"This explains why my coffee tasted odd this morning." Stephen sighed and rubbed a hand over his face. "I guess one of the Kartoth demons really did get through to me."

"The demons who feed on life forces. That's what's possessing you, and now you're cold and pale and barely have a reflection." Tony pointed. "Tell me I should be thinking of something other than what I'm thinking."

"Unfortunately, you should be thinking it."

"Vampires?" Tony sputtered. "They're real?"

"Obviously." At Tony's blank stare, Stephen rolled his eyes and continued, "They appear in nearly every cultural mythos around the planet. Is it more likely that a similar fictional creature was independently imagined a hundred times over, or that they were all describing a real entity?"

"Vampires?!"

"Calm down, I'll get this under control. Your heart can stop racing any time, now." As soon as the words left his mouth, Stephen realized it'd been a mistake to say them.

"You can actually hear my heart beating, can't you?" Tony shook his head in disbelief. "Vampires. Jesus Christ. That's..." Cutting off, Tony frowned thoughtfully, crossed his index fingers at a ninety-degree angle, and started moving the symbol closer to Stephen's face. "Feel anything?"

"What exactly are you hoping to accomplish?" Stephen asked as he eyed Tony's hands.

"I mention Jesus, I'm gonna test a cross." Tony did drop his hands back to his sides, thankfully, but his gaze was no less suspicious. "Running water. That's a thing. They can't cross it. Right?"

Stephen considered the Hudson and East Rivers on either side of Manhattan, then shrugged. "The rivers don't seem uniquely threatening, but I don't think anyone should be touching _that_ water, anyway. Besides, I'd just portal myself."

"Sun?"

Imagining daylight did generate an instinctive reaction. "Hmm. Yeah, I really don't want to step outside, now that you bring it up. Damn." It had probably been no coincidence that the Kartoth demons had waited until dusk to break through the dimensional walls; ultraviolet energy must damage them.

"Oh my God." Tony gawked at that confirmation before adding, "Glitter?"

"That's not real vampire mythology," Stephen snapped. "Absolutely not."

"Blood?"

"Blood?" Stephen repeated, taken aback.

"It's kind of the key element, right?"

"I am a doctor," Stephen archly replied. "Feeding on people is not a possibility." Now he felt guilty about mentioning bolognese sauce to Christine after her messy surgeries.

Tony pulled back to study him. "You didn't say you didn't want it, you just said you wouldn't do it. That's a different answer." As Stephen began to protest that they were essentially the same response, Tony spoke over him to ask, "So then... that thing possessing you doesn't want blood? You can just have what's in your fridge?"

Eat what was in his fridge? Meaning, all of that food that now repulsed him? ...Fine, yes, so there was a temporary sustenance problem, but it wasn't like he actually _wanted_ any of the rich, thick life fuel that he could hear pump with each heartbeat. "Dammit," Stephen groaned as he pushed down that sudden impulse. 

This was one of the more annoying situations that the mystic arts had presented to him. He looked up to the ceiling, sighed, and then insisted as he looked back down, "It's a simple exorcism. I'll have it completed shortly now that I've identified the problem."

"You actually want my blood, don't you?" Tony's eyes narrowed. "I've gotta admit, this is not a situation I came prepared to make my customary charming quips about."

"It's a simple exorcism," Stephen repeated. "Now if you'll excuse me, I'm going to go find the right books."

"Shouldn't Wong be on board with this?" Tony called after him as Stephen headed for the stairs.

"At a conference," he called back. Conclave. Whatever.

"Oh, he's got great timing!"

That was the last that Stephen heard from Tony as he closed himself into a small study. The Cloak had swept in to join him, and without trying to hide his tired expression Stephen informed it, "I'm going to need you to visit the library at Kamar-Taj." After the Cloak leaned in to survey his altered eye color, he added, "Yes, about that. I appear to have been possessed by a minor exposure to vampirism."

The Cloak pulled back in surprise.

"I know. It's completely ridiculous, but it needs to be resolved. I'm concerned that if I visit the library myself its wards will be tripped by my current demonic stowaway." Without knowing anything about his possessor, Stephen couldn't be sure whether Kamar-Taj's magical protections would simply send up an intruder alert or whether it'd launch the instant full assault on a perceived dimensional breach. With the librarians away at their conclave, there were probably more active security wards than usual, too.

"Yes," he insisted to the Cloak as it hung there in shock. "Vampires. Really. I know it's stupid. Can we please get to work?" As the Cloak bobbed its collar and proceeded obligingly through the portal he created, Stephen opened the most likely tome the New York Sanctum had on hand. As he suspected, holy water had no effect on true vampires, but silver actually worked outside of folklore. As did ash wood, potentially, and hawthorn, and aspen, and...

"A little more clarity would be nice," Stephen grumbled as he tried to make sense of a hundred conflicting cultural lores on how, precisely, vampirism could be overcome. Like he'd told Tony, he was sure that all those tales reflected encounters with actual creatures. Clearly, though, Kartoth's particular breed of life-suckers weren't the only ones to have visited Earth. Different demons had different weaknesses.

"Well," Stephen sighed as he began generating a massive list of potential approaches, "better get started."

After a lengthy, unsuccessful stretch of trials, his stomach felt like it had tied itself in knots. Water barely eased his parched throat and seemed to heighten his hunger with each sip. "You have got to be kidding me," he muttered as it became clear that his stowaway was now outright demanding to be fed. "No. Absolutely not."

The next time he swallowed, it was like a razor slid down the inside of his throat.

"Go to hell," he hissed at his passenger. "Or I'll send you there myself."

The next round of books the Cloak retrieved presented more suggestions, but no clear answers. He exchanged the clear duds for these new hopes, entrusted the Cloak to ferry titles back to Kathmandu, and returned his focus to the notes-covered table.

A moment later, there was a knock on the front door. Stephen didn't bother with his typical showboating of walking down the grand staircase; he instead teleported Tony straight to his study. Without looking up from his notes, he said, "Please tell me you have found something insightful and useful about those energy signatures."

"No. But I handled something else."

Frowning, Stephen looked up just as Tony set a brown paper bag down on the desk. 

A second later, his entire being seemed to scream like a wild animal as Tony lifted an object out of that container: a bag of human blood ready for medical use. He needed a few seconds spent behind closed eyes to collect himself. "If you tell me that you got Christine involved in this, Stark, so help me God."

"Hmm, yeah. That probably would have been faster." Tony gestured at the bag. "But no. I'm just an image-obsessed billionaire who heard that you can make a mud-and-blood mask to take the years off."

"That's repellant."

"Yeah, that's pretty much the reaction that Happy gave me. But I insisted and he tracked some down." Tony wiggled the bag at him. "From the look you're giving me, you can't pretend you don't want this."

Even though it felt like more razors slicing his esophagus open, Stephen swallowed hard and refused to give Tony the satisfaction of being right. He also refused to drink something that should instead be used to help people, and oh yes, it was _blood._ And therefore a _biohazard._ And... _gross._

"Oh, just stop being stubborn. From looking at you, you clearly need this, so drink your damn blood." Tony paused to consider that, then sighed deeply. "You make my life so weird."

"I am already trying promising methods to get this thing out of me," Stephen protested. His hand gestured broadly at the aftermath of his attempts. "I will land on the right one without giving in to this possession. Take that stupid thing away. Now." His throat cleared. _"Now."_

"If you're going to act like a child," Tony replied and extended the blood bag, "then just drink your Capri Sun." 

Tony's hand twitched. The bag wiggled again.

A faint noise emerged from the back of Stephen's throat. He wasn't sure if it sounded more panicked or disgusted. Need clawed at his stomach, regardless. He could abruptly feel how chilled his body actually was. 

"Come on." 

Stephen couldn't hold back another strangled noise. The study's dim lighting gleamed off the bag's glossy plastic. Dark, rich liquid moved inside. Like fine wine.

"Come onnnnn."

"Stay right here, you are not allowed to watch this," Stephen ordered as he grabbed the bag with one hand, opened a portal with the other, and closed it after stepping into the kitchen. _Oh my God, I can't believe this is happening,_ his brain screamed as he clipped the protrusion that would normally hold an IV tube, then flipped the bag over and let it begin draining into a cup. But once he'd started, it couldn't stop. It was like he was under twenty feet of water and his burning lungs demanded air.

 _This is not happening!_ No matter how much he tried to deny it, he was now feeding the damned thing that had taken possession of his body. The blood running down his throat was as good as a first breath after reaching the water's surface. It sated every urge that he'd spent a day building. Thirst, hunger, cold, exhaustion: they all fled as he desperately swallowed.

As the cup emptied and the demonic urges eased, Stephen's human nature returned to the forefront. 

Well.

This was absolutely disgusting.

Gingerly, he lifted the cup away from his mouth and reached for a paper towel. There was something wet on his lips but he refused to lick it away. "Breathe," he told himself as he set the cup down and his stomach roiled. The demon might want this, but this was _his_ body and that was not a meal it could handle. Swallowing hard against sudden nausea, Stephen let his mind go blank except for a steady countdown. _Ten... nine... eight..._

By the time he reached zero, things had settled. Somewhat. The scent of blood now repulsed him, though, and so he poured out the remaining inch in the cup without actually looking at the sink. "Yeah, that just happened," he tiredly admitted as he rinsed things out, then used more paper towels to grab the bag and move it to the trash.

"So you actually drank it?" Tony asked when a portal opened back to the study.

Stephen looked back at him hollow-eyed, but said nothing.

"Here," Tony added. "I got more. You probably want to put them in the fridge before you come back up."

Still saying nothing, Stephen accepted the bag as Tony handed it through the portal, stowed the blood next to some cold cuts he would now never eat, and returned to his study. As soon as he took a seat at his desk, his head dropped onto his folded arms. "You will never mention this."

"Was it gross? Vampire or not, I just can't believe that wouldn't be gross."

"You will _never_ mention this."

Tony considered him, then continued, "Are you positive you don't want me bringing your buddy into the loop? She is a doctor, right? She probably has some medical ideas—"

"You," Stephen ordered as his head snapped back up, "will never mention this." Christine could never learn about this extremely stupid crisis. She already fretted over the normal fallout of his mystical struggles. She even worried about how Stephen still avoided cars, not that he _needed_ them with portals at his disposal. Learning about vampires—vampires!—would be far too much. He'd never hear the end of it.

"Fine." Tony held up his hands. "I will never mention this."

"Good." Stephen dropped his head back onto his folded arms, sighed heavily, and mumbled toward the desk, "Thank you."

"What was that? You're all muffled."

"Oh, you heard me."

"I did. I just wanted to hear it louder."

Groaning, Stephen forced himself up again and met Tony's eyes. At least the other man seemed discomfited by his unnaturally golden stare. "Thank you, Tony." After another pause he added, "I could use some help."

"You don't say."

"Don't push the man possessed by an inter-dimensional vampire."

"Well," Tony said as he grabbed a chair from elsewhere in the study and dragged it close, "the way I figure it: I was going to be in that Shakespeare audience whether you were there or not. So were all of the very nice charitable donors who are paying for my clean energy showcase. If you hadn't been there and those demons had been able to just pour in, we'd all be dead. Right?"

"Oh." With all these distractions, that part of the night had fled his mind. "Yeah. You'd be a shriveled, aged husk in a morgue somewhere."

"Specifics not needed, thanks." Tony smiled blandly. "So... let's say that my helping you now is payback for me not ending up as a shriveled Shakespearean husk." Anticipating his retort, Tony added, "But I will keep Miami in reserve. You still owe me something for that."

Stephen returned a tired smile. The two of them had been involved in an epic plan to save the universe, after all. They could certainly handle something as small as this. "That's fair enough," he said as he extended his hand.

"You really are freezing," Tony pointed out after they shook.

Sighing, Stephen looked back across his study. "Yeah, well." He'd tried so many of the suggested fixes already, but had discovered mild reactions at most. Clearly, the Kartoth brand of vampire needed a tailored solution to expel it from his body. Masking itself had given it the chance to integrate deeply. "I'm working on it."


	4. Chapter 4

After that, Tony needed a while to catch up on the experiments so far. The Cloak returned again while he was investigating, but Stephen suspected that its latest selection of books would simply be more to read through. He thanked the Cloak, still, but the gratitude sounded exceptionally tired.

As the Cloak flew back into the portal to Kamar-Taj, Stephen slumped against his chair. "So. Yeah. I'm going to need some help. As you can see, this research is more complicated than I expected."

"Should we track down Wong?"

That was something he'd wanted to avoid. After Stephen's initial overconfidence with tackling the dimensional breach, this outcome would just be too much to share. It didn't matter that scarcely anyone else—including Wong—could have handled the raw power necessary to do that emergency patch. His second visit to the park had been exactly the sort of confident, accomplished defense expected of a true master of the mystic arts... but it had followed a mistake with the first trip. And Wong would definitely remind him of that.

Stephen considered that embarrassment potential, but then he considered the blood bags lurking in his fridge. It probably wouldn't be too long until his passenger demanded another one. "Yes," he admitted. "Wong would definitely help." If Wong got this thing out of him, then he could be the target of a few jokes.

"Where am I flying?" Tony instantly asked, but made a noise of realization after sparks appeared. "Never mind. You know, transportation is a huge source of pollution. You guys could really help out with—"

"Can we focus on the current crisis, please?"

"Right. Where is that?" Tony asked as he squinted at the greenery visible through the portal. "A jungle?"

"They're in a temple near Tikal in Guatemala." Stephen gestured at the air and glowing sigils erupted. As Tony obligingly used his smart watch to record their forms, Stephen explained, "You're looking for the building where moss refuses to grow in those shapes. Do _not_ knock on any other door."

Off his emphatic warning, Tony frowned. "Are you sure you don't want to come—" Stephen's resigned sigh, complete with a wary look through the portal, gave him pause. "That's a sunny day through there, isn't it?"

"The creature's stopped hiding, by this point," Stephen explained. Had it happened when he drank the blood? Probably. "Now I can feel it. It's integrated with every last cell of me, and so every last cell would be damaged." Even indirect sunlight triggered new survival instincts. There was zero chance he would ever willingly step into that blinding fire.

Speaking of that, he needed to take care of a safety issue. His hand flicked and every blind and curtain in the Sanctum closed. Even the circular window inscribed with the sigil for New York faded to an opaque shade. 

"Here," Stephen added and handed Tony one of the silver knives he'd used to test various vampiric possibilities. Its carved handle was also inscribed with the New York sigil. "They'll question you when you knock. Show them that and mention my name."

Tony took the knife with greater solemnity than he'd shown so far. "I'll get this done."

"Thank you." That was more sincerity than Stephen had shown so far, too.

Half an hour later, all that solemnity and sincerity was for nothing. "I checked every single building in that area," Tony promised. "Even the ones near tourist paths. There was only one that had gaps in the moss that looked like your symbols... and it was empty when I walked inside."

"Dammit," Stephen groaned. "Right. Wong said they were meeting first, but then that'd move into retrieval. I have no idea where in the multiverse they might be hunting through for books right now."

Tony paused, then shook his head slightly. "Uh, okay, sounds like a fun time. Is there any way to find him?"

"Yes. I can begin that dimensional search, but I don't know how long it'd take. Any time spent doing that is time spent not testing these methods. So now I have to make a choice as to which is the smarter path to pursue."

"Test the methods," Tony said after a second of thought. Holograms erupted from his smart watch and he began typing on the keyboard that now hovered under his fingers. "Let me put together a recommendation algorithm based on your findings so far. We'll narrow it down efficiently."

"All right," Stephen said after a pause of his own and put Wong out of his head. Truthfully, he did prefer to take everything into his own hands rather than wait for someone else to show up. He suspected Tony was much the same. Wong might be able to do this research faster, _when_ he showed up, but the two of them could be working on things _now._

A second later, he realized that meant he was truly, wholly counting on Tony Stark in his hour of need.

Stephen exhaled and tried to focus. "I suppose the worst-case scenario is that I'll need another bag from the fridge if this goes on too long."

"Right," Tony said as he began running his scanners over Stephen's notes and any open books. "No big deal."

"Oh, huge deal," Stephen corrected. "But doable." He'd suffered much worse in his life than consuming a little blood. If he'd been blasted into component elements _more than once_ in service of the world's survival, he could handle o-negative.

Tony snorted but didn't look over from his work. "I knew it had to be gross."

"It... is really gross, yeah," Stephen admitted.

Hours passed and data was analyzed. As night fell outside the covered windows, Stephen announced their best next step: returning to Central Park to test the power flows there. Measuring some of these possible solutions against the actual energy of Kartoth would be invaluable. 

Though he obligingly stood, Tony wondered, "Should you grab another bag before you head out?"

"I should be fine for a while," Stephen said, shaking his head. He didn't want to drink a single drop that he didn't have to.

"Right," Tony slowly said, "but you were a tiny bit... tense by the time I got you to take the first one." When Stephen didn't reply, he added, "And we're about to head into the middle of a bunch of walking blood bags."

"Never call anyone that again."

"I'm just saying," Tony said and held up his hands. "If you're tense, you can't focus. If you can't focus, you probably can't manipulate energy. If you can't manipulate energy, then I don't know why we're heading over there."

That made sense, unfortunately. "Do I look tense?" Stephen wondered and leaned back to catch sight of himself in a mirror across the room. His eyes rolled a second later as he saw the back of his chair tip into view, but not him. Not even a color blur.

God, this was annoying.

(His phone camera confirmed that he looked tense.)

Tony seemed to treat that sight of full invisibility more seriously. Seeing Stephen's total absence of a reflection was a genuine shock to him. "It's actually gone." His gaze fell to the floor in thought, and when he looked up, deep concern lined his face. "Are you still..." He swallowed. "Alive?"

Stephen obligingly placed two fingers against his carotid artery. "Of course I." He had to wait for a heartbeat. "Am." The needed pause tipped him toward concern, though, which fermented into something deeper. He'd really expected this to be a simple exorcism. Instead, it was a sly, powerful infection with a hundred potential cures. There was actually a chance that he wouldn't get this out of himself tonight.

Worry still painted Tony and seemed to intensify by the second. "I can help with recommendation algorithms all you want, but I don't know the theories behind what's going on here." He stepped closer. "I'm getting the feeling that this is more dangerous than you've been letting on."

Stephen looked away. He could feel the hint of a chill in his fingertips, now that Tony had pointed out that he might need more blood. "It's unfortunately more dangerous than I initially assumed... but still manageable." It _had_ to be manageable. He was a master both of one of Earth's three Sanctums and of the mystic arts. Some insignificant demon in a swarm could not possess and bring him down after his shields dropped for _half a second._

He simply refused to lose to this. It was too ridiculous.

And yet, he could feel more cold gnaw at his fingers. Tony was right: by the time he started working with energy in the park, hunger might well leave him distracted. Drained. Useless. "I'll meet you in the front hall," Stephen said after another aching pause. "I... will stop by the kitchen, first."

Tony nodded, but stayed thankfully silent.

"You are going to suffer for this," Stephen informed his passenger as he stepped into the kitchen. "Deep, meaningful suffering. I just saw Titus Andronicus, you know. It was dark. I'll get creative." He flung the door open, retrieved cold plastic from its paper bag, and slammed the fridge shut again. "Whatever your weakness is," Stephen finished as he raised a pair of scissors, "I'm gonna have some fun with it."

The only thing worse than lukewarm human blood, Stephen soon realized as he stared at another full glass, was chilled blood.

"I'm already cold," he rationalized as his eyes wandered toward the microwave. "It's summer, but I'm about to head outside. And summer or not, it's night. No. Why am I arguing with myself about this? I can't put this in there. I'd have to throw out the microwave. I can't do this."

His head tilted as he considered the thick, dark meal... the thick, dark _liquid_ in front of him. It just wasn't right. It smelled dark. Cold.

Dead.

"I can't do it... like this," he soon groaned, and turned. 

The heat-craving _something_ inside of him glowed with satisfaction as he retrieved the warmed glass. Stephen, however, prepared for another assault on his senses. He'd been frantic earlier and so desperation had initially masked how awful the first blood bag was. His second drink was being taken on a more reasonable, less hungry timeline. This would be even worse than before.

Oh, Stephen thought in faint surprise as he swallowed. It wasn't bad at all, actually. Heating it made a huge difference from that tepid sludge earlier. He soon set down the empty glass and waited expectantly for any more nausea, but it never came. "Heat worked," he reluctantly admitted as he rinsed out the few drops left in the cup.

_Or my system has just adapted to it by now._

Stephen sighed as he reached over to the bag and tossed it in the trash. Yeah, he'd been trying to avoid that possibility.

"Good to go?" Tony wondered as Stephen joined him.

"Good to go." Before he could form a portal, Stephen frowned at Tony touching his own bottom lip like it meant something. "Oh, right," he realized and licked away one remaining drop of blood.

"Ew," Tony said as they stepped into Central Park.

Stephen shrugged and looked around. As he'd expected, the Shakespeare stage was dark tonight and so there were few people in the area. "They're your bags." He probably should have reached for a paper towel in the kitchen, but he felt good again: warm, full of energy, and able to handle anything. Bothering Tony fit right into that bright mood.

"So," Tony wondered as Stephen began feeling the open air. His smart watch lifted to take readings on all of Stephen's energy manipulations. "Vampires. Are werewolves and zombies a thing, too?"

"You know, you and Christine wondered about the same trio."

"Well, they are the big three." Tony paused, and after Stephen stayed quiet to focus on the particular energy ripples unique to Kartoth, he insisted, "But seriously. Werewolves? Zombies?"

"Werewolves are extremely rare." This energy frequency didn't feel at all like how iron had resonated when he tested it, but remembering his earlier trials, silver did seem to have potential. Perhaps he'd written it off as a possible solution too quickly. "As for zombies, yeah, necromancy is a huge industry."

"A huge industry?" Tony echoed.

"Huge. There's a black market for guides and materials in a dimension very slightly adjacent to ours. We always try to round people up before they cause trouble here, but..." Huh, Stephen thought as he felt again for the echoes of energy on the other side of his patch job. Yeah. Silver really did feel like the way to go. He just needed to figure out the right application, now.

"Unicorns?"

Stephen couldn't help but laugh. Tony's tone was incredulous, but this was far better than he'd done with learning about magic in what had previously seemed like a mundane world. "Extinct, but you would not have wanted to meet one."

"Mermaids?"

"As in a creature who's half-fish, half-human?" Stephen turned away from the energy fissures, satisfied with what he'd learned, and shook his head. "Not extinct, but you _really_ don't want to meet one."

Tony seemed to balance on a knife's edge between accepting all of this fresh knowledge and deciding that it was just too unforgivably out-there. Thankfully, he decided to laugh and ask, "So, not a hot cartoon girl in a seashell bikini?"

"Definitely more Innsmouth than Disney," Stephen agreed. "You don't even want to know about Bigfoot."

Tony hesitated, then nodded. "You know what? I'm totally going to believe you on that one. How are you feeling by now?"

He had a plan, he felt good, and everything was headed in the right direction. "Much better." 

"And that's all because of my blood," Tony said smugly. "I knew you needed to listen to me when I showed up with those bags. This is maybe the weirdest thing I've ever bragged about, but I'm still going to brag."

A sound floated past them like a missed note on a piano. Frowning, Stephen turned slightly and peered into the night. 

"And I have bragged about some _things,"_ Tony laughed.

Something was wrong.

"Like there was this time with Rhodey," Tony continued, "and he didn't believe that my nanotech could block bruising with how thin it was, so I got a bunch of peaches..."

Whatever he said next was meaningless. Those discordant notes were like a soundtrack to a horror movie, now. Stephen's narrowed gaze roamed the darkened park in search of whoever was causing it.

_There._

"What," he demanded in a low voice, "do you think you're doing?" He didn't even remember moving.

The man he'd surprised with his sudden arrival struggled against Stephen's grip. His shirt was bunched in Stephen's fist so tightly that seams threatened to rip. It rode up around his torso, exposing the skin there. The scent of blood drifted free when he struggled against the rough tree bark behind him.

At their feet, a homeless man had his arms wrapped around his ribcage. Each breath wheezed. His attacker had clearly surprised the man while he was sleeping. With no one there to judge him in the darkness, violence had seemed like an amusing indulgence. The sadistic laughter as he attacked his victim had been that horror soundtrack that floated to Stephen's ears.

"Fuck off," the man tried to say, but it came out all strangled. His shirt had compressed so tightly that he could barely draw air.

"How's it feel?" Stephen wondered as his other hand pressed against the man's throat. A startled cry croaked free of his windpipe.

This hadn't been self-defense. This was someone preying on an innocent victim. Reveling in how much stronger he felt. Treating another human being as disposable, and not caring what happened with a helpless life after theirs intersected.

"How's it feel?" Stephen demanded as his hand around the man's neck began to tighten. 

"You don't want to do this," murmured a quiet, sure voice at Stephen's side.

The sound made him blink in confusion, and then blink again as it felt like he was waking from a bewildering dream. Without moving his hands, Stephen turned to look at Tony. "What? I..."

"Let him go," Tony said carefully. His hand rested on Stephen's arm that still clutched the man's windpipe. After a moment, it began to apply gentle downward pressure. "Open your hand."

_What am I doing?_ Stephen wondered as he looked at the man's face. It was purple, desperate, and pleading. Like the skin he touched was suddenly searing, Stephen's hand opened and jerked away. The hand holding the man's shirt released a second later.

"I got your face on video and I've already run a recognition sequence," Tony continued in rigidly controlled tones. "So Paul, why don't you go turn yourself into the police and say you did something bad, and spend tonight in jail, huh?"

Paul didn't move. His terrified eyes didn't even blink as he stared at Stephen.

"You do that," Tony continued, "and we'll all forget this ever happened. Sound good?"

Without another word, Paul turned and ran.

"Tony," Stephen whispered. He'd been able to see the park in the darkness, but it blurred through suddenly teary eyes. "I don't know what I was doing. I..." He looked around vacantly. Right. Someone was injured. He needed help. Stephen could help. "Let me check that."

When he knelt next to the injured man and Stephen reached out to gauge the situation, a pained noise erupted. Despite his injuries, the man had cringed away as soon as Stephen came close. The motion jostled his wounds. 

They smelled of blood.

Oh God. This man was terrified of Stephen after he'd watched him nearly kill someone, and now Stephen could _smell blood._ A yawning hunger opened as Stephen stumbled to his feet and backed away. "Help him," he added with a shaky gesture to Paul's victim. "I have to go."

He needed to stay inside the Sanctum. It had magical shields. It was specifically designed to protect against magical assaults on Earth. So long as he was inside the Sanctum, the demon wouldn't be able to take over. Not like this.

When he stepped back inside, not bothering to see if Tony was helping the injured man back in the park, Stephen's breath began to speed. He would have killed Paul. He would have just closed his hand, used the strength that didn't belong to his own body, and crushed his windpipe like crumpling an empty can.

"Something is very wrong," he gasped. Realizing the Cloak was there and approaching him with concern, Stephen demanded, "We need to find every piece of silver in the building, right now. One way or another, I'm getting this damned thing out of me."


	5. Chapter 5

"Damn," Stephen snapped and slammed the silver needle against the table. Injection sites dotted his skin. He was positive that being pierced with silver was the way to go with this, but no matter where he tried stabbing himself he couldn't get a reaction.

His head sank into his hands. Nearly a minute ticked away on the clock.

"What am I going to do?" he whispered. He'd nearly killed someone. Worse, he'd enjoyed it while it was happening.

Earlier, Tony had called people 'walking blood bags.' Now that was all he could picture. There were so many worthless people out there who only existed to hurt others. So long as their hearts moved, they'd kill. Rape. Enslave. Abuse. 

It'd been so easy to hold that man down. He could walk into the remaining night hours and find someone else who _didn't deserve to live._ They'd have no chance against him as he held them down, pierced an artery in their vulnerable neck, and felt their racing pulse flutter into dead nothing as heat poured down his throat. It would be so easy. So easy.

So... fun.

"Nngh," he whimpered and closed his eyes.

A gentle touch on his shoulder drew his attention. Stephen turned to the Cloak as it hung there. After a still, silent second, it wiped away a tear on his cheek.

"Is there anything else in this entire place," Stephen barely managed to ask, "that is made of silver?"

The Cloak considered that for a long moment, then looked up to the wall of the study. Stephen followed its motion.

Ah.

The mirrors.

Of course. This would do it. The silver backing to this mirrored glass rejected the being inside of him. If it wouldn't show his possessed reflection, then surely it could also expel the demon. Desperate with hope, Stephen rushed across the small room and tried putting his hand on the glass that refused to reflect him, then lifted the mirror off the wall and touched the silver backing directly.

When that didn't work, he threw the mirror to the floor. The Cloak jerked away as it shattered, but Stephen leaned down, grabbed one of the largest pieces, and raked it across his forearm. "Get out," he hissed as he pressed the shard's edge into the wound he'd made. Unnaturally thick blood drained around it. Silver had to be filtering its way into his system, and if it wasn't, he just needed to work at it more. "Get." The shard pushed harder. "Out."

"You don't want to do this, either."

Stephen looked up to the study door. "Is he okay?" he asked Tony in a wavering voice. He didn't stop pressing the fragment against his arm. It hurt. That didn't matter.

"He's okay," Tony confirmed as he took slow, measured steps into the study. "I got him some help. He'll be good. Now I want to get you some help."

"I am trying to help myself," Stephen hissed as he sliced a new wound and held the glass there. "Silver is the way to fight this thing, and so I am going to dig it out."

"I think you know that this isn't working," Tony said after a considering pause. "So how about you hand it over and we think this through. Huh?"

After another second of pain, Stephen threw the shard against the floor. It hit carpet and rebounded instead of shattering, then landed near Tony's foot. The mirrored portions reflected flickering candles. His smeared blood made holes in the light.

"I nearly killed him," he said hopelessly and collapsed into a chair. "I wanted to."

"And you stopped," Tony said as he inched forward, murmured something to the Cloak, and kept moving closer. "Now you don't want to kill anyone. You've got back your control."

"I have control inside the Sanctum," Stephen confirmed, but panic still fluttered in his chest. He didn't know if anything else moved there, now. If his heart was beating, it was terribly slow. "For how long, though? I still need to drink blood here, and it seems to get worse every time that I do. Eventually I'll be as dangerous inside as I am outside.

"I should have found Wong," Stephen murmured a moment later. "I'm losing it. Our whole plan involved me analyzing those books, but I can't focus. I can't think. All I know is that I have to be out there right now. The sun's down, but there are still all of those lives just walking... outside my door..."

With another desperate groan, he pressed his hands to his face and tried not to think of blood.

"Right. Um." Tony's uncertain noises trailed into nothing, but eventually he suggested, "What if things are easier during the day?"

Stephen looked up. 

"It sounds like that thing inside of you loves the night. So, shouldn't you have more control during the day? You'll be able to focus when the sun's up and we can get this done before tomorrow night." 

Yes, these new instincts of his did want to hide away from the sun. "Maybe," Stephen shakily agreed. "Or maybe I'll just get this far gone again during the day, and after the sun sets..."

"Or maybe you won't." Tony swallowed. He tried to smile and make it look real, but a trickle of sweat wound down his temple. Despite his calm tone, he was terrified.

Human eyes wouldn't have been able to make that out that sweat droplet in a dim room.

"Try to get some sleep," Tony suggested when Stephen didn't respond. "I'll stick around here and do an all-nighter with the algorithm. But I really, really think you should rest up instead of pushing yourself. When you wake up to a bright, sunny morning, it'll be you in the driver's seat."

Stephen looked away. The only distraction from Tony's words was running his tongue across his teeth and wondering if the canines felt sharper. He didn't want that particular distraction. "Why are you doing all this?"

"Well, I'm not a Shakespearean husk. I said I owed you for that. Debt's not paid, yet." After a considering pause, Tony stepped forward and added, "Plus, you'd do the exact same thing." 

Stephen looked back over, met Tony's eyes, and studied him before replying. "You don't have your suit."

A line of confusion wrinkled Tony's forehead. He laughed slightly. "You... still owe me for how annoying it was to get back from Miami, yeah."

"That's not what I meant." Tony kept blinking under the alien-colored gaze the demon had given Stephen. That motion made Stephen aware that he _wasn't_ blinking. "I don't remember moving in the park, so I know I must have run too quickly for you to react to. I'm unnaturally strong. And I still have my magic."

Another bead of sweat trickled as Tony smiled. "Show-off."

"And you don't have your suit."

"Rub it in, why don't you?"

"If I lose it again, you will die." Stephen blinked once, then went back to staring. "Do you realize that?"

For an answer, Tony grabbed one side of his t-shirt collar, pulled it down, and tilted his neck in the other direction. "You're not gonna do it. You're in control. You were out of control when I got here, but you're in control now. Then the sun's gonna come up and you'll be even more in control. I'm fine."

Stephen swallowed hard. Golden eyes trailed down the curve of Tony's throat. At one spot, he could make out the slight flutter of a pulse. The sight was as captivating as a stopwatch swinging him toward hypnosis.

_He's not hurting anyone_ , a voice insisted. _He doesn't deserve to die._

With a deliberate motion, Stephen closed his eyes, took a deep breath, and said, "You should probably stop stretching your neck like that."

"See?" Tony asked. His hand shook as he let go of his shirt. Sweat ran down both of his temples, now. He'd gambled with his life and had no idea how the roll would turn out. "I knew you'd hold on."

"I'm going to bed until sunrise," Stephen replied after another long, silent moment of studying Tony. "Focus your work on silver. It's the substance we need to use, but I can't figure out how to apply it. And... thank you."

"Sure." Tony nearly let him leave before adding, "I don't remember everything about Thanos, but I'm pretty sure you counted on me to bring you back from the dead once before. I'd hate to break my streak."

Stephen smiled faintly, inclined his head, and added, "Good night, Tony." As he turned, he saw a ripple of crimson. Around the perimeter of the room, on Tony's apparent suggestion, the Cloak was gathering up all the sharpened silver and broken glass that Stephen might use to hurt himself again.

The wounds on his arm were nearly gone by the time he got to his bedroom. Stephen looked at the unnatural healing, sighed at yet another confirmation of how far gone he was into this infection, and practically collapsed onto his bed. 

They had one day left with this, or he'd be too far gone to hold onto humanity. That was clear. 

These demons were far more dangerous than he'd ever suspected, nor had Wong known that something so deadly lurked inside Kartoth. Perhaps he would have been able to resist if they'd made him feel awful from the start, but he'd only felt mild discomfort before the infection really took hold. After that, it was too late... and worse, after that it felt _good._ Pleasure was so much harder to fight than pain.

It had felt _good_ when he'd stopped Paul in the park. When he'd taken away the man's breath and made him feel the terror that his victim had experienced. It still felt good to think about hunting down more dangerous people out there.

What if he really couldn't get this out?

He did still have his magic. "Would you still accept me as your master?" Stephen wondered toward the empty room. Nothing in his new instincts told him that he should stop facing down mystical threats. He was as adept with magic as ever and had sudden new physical abilities. He might actually be _better_ suited as a Sanctum master than he was before.

Except for how he wanted to murder murderers.

But then... that was normal, wasn't it? He'd always been odd among students of the mystic arts for treating killing as an absolute red line. They saw themselves as soldiers. Soldiers killed the enemy. Right?

Murderers... rapists... human traffickers... they might not be mystical enemies, but they were enemies of all that was good in the world. Their blood would taste the same as anyone's. No one would miss them. The people who'd reveled in their power over others would feel completely overpowered by him.

Then they'd die helpless in his arms. Absolutely helpless. The Sanctum could adjust reality as needed to remove any DNA evidence, and Stephen could toss their corpse through a portal into the middle of the Pacific. Like taking out the trash. It would be so satisfyi—

"Oh," he said and narrowed his eyes at the ceiling. He could identify the infection coiling around his thoughts. "You're good."

It was harder to fight off pleasure than pain and daydreams lasted more comfortably than nightmares. Just one thought along this line, and the demon had found exactly the right notes to hit to hold his attention. It didn't care whether he drained innocents or murderers. Stephen Strange was its food delivery service, now. He needed to do his job however he had to be motivated.

Well. He was going to go to sleep and wake up when this thing was weakened. And they _would_ root out this infection. They _would._ Because he had control. Really. Even with Tony offering himself like that with his neck helplessly exposed, Stephen hadn't wanted to—

_Pull him close, so tight that he can't get away. Feel the heat of his body. Taste the skin where his pulse fluttered. Lick the slight salt of his sweat before kissing with daggers that pierce deep as he cries out and—_

"What in the hell?" he demanded of his demonic passenger. "Tone it down. You amped up the endorphins a little too much on the pleasure bait, there."

At least for a few minutes, it seemed like he'd successfully wriggled off the hook. Stephen took that time to fall asleep, hoping that neither dreams nor nightmares would follow.

Neither did. He slept like the dead.

(Bad phrasing. He should not use that phrasing.)

"How's it going?" Stephen wondered as he walked back into the study. He didn't feel wholly like himself, but like Tony had hypothesized, it was better than he'd felt during the night. Tony was up and working, though he looked more than a little exhausted. The Cloak passed objects over when he held out his hand.

"I had a courier bring over some of my adaptive nanos," Tony said without looking up. He seemed to be in the middle of an experiment. "A test batch silver-plated themselves and then assaulted the blood you left on that mirror shard. I thought a dispersed attack might be the way to go."

Considering that, Stephen slowly nodded. "Like an antibiotic hitting my whole system at once."

"Basically, yeah." Tony looked up, ran a hand over his day's growth of stubble, and added, "Was not a total success."

That'd probably been too much to hope for. "What was the partial success, then?"

"The cells looked a little more normal," Tony admitted after a pause, "when the nanos emitted an electrical field to cause slight trauma."

"So. Attacking the infection might mean _attacking the infection._ " Stephen nodded slowly, then pointed out, "Like I was trying to do with that mirror last night."

"Sort of," Tony hesitantly agreed. "But. You know. With an actual plan besides 'ow, ow, ow.'" He folded his arms and studied Stephen. "How are you feeling?"

Well, Stephen no longer felt any tempting rationales for why it made sense to become a mystical vigilante. That would surely return as the sun set, though, and now he was desperately hungry. Consuming another bag would probably ratchet the infection's strength up another notch, but he couldn't possibly put it off. He couldn't let himself grow desperate enough to start eying that fluttering pulse in Tony's neck again.

He'd woken up with a bite capable of putting that artery to good use, after all.

('Good use.' That was not the right wording to use. Bad use. Terrible use.)

"I feel like I should make another trip to the kitchen," Stephen eventually said. "And then we can figure out how to make a generalized attack with silver."

Tony offered a thumbs-up. "Sounds like a plan."

Blood now smelled unfortunately delicious when it was heated. Unlike the day before, though, the bagged blood tasted as insubstantial as cotton candy. Though Stephen's hunger did ease as he tilted the glass, it wasn't actually sated. Heating the fourth and final bag from Tony's delivery was probably a bad idea, but he did need to keep his mind focused in the final research push.

"Let's knock this problem out," Stephen announced as he returned to the study. _Before this latest meal changes my thinking too much more._

There were runes, Stephen mused a few hours later, specifically designed to affect entire incorporeal beings. Such runes hadn't seemed like the right match yesterday, but perhaps combining the right runes _with_ silver would let him expel this infection. Hopefully they could find that right combination quickly, though; it wouldn't be too much longer until hunger returned. Tony could get more blood for him, but the blood in those bags was hollow, flat, and dead.

'Dead.' Damn. That was the problem, wasn't it? That was what the demon demanded now, even with a brilliant sun overhead: live blood, coming straight from an artery and fueled by a beating heart. Thick. Rich. Unmistakably alive. The thought of heat pulsing in warm jets was almost too much to take, and Stephen gripped the desk and held on until humanity return to the forefront.

"Tony," Stephen said in a calm, controlled voice. "I'm going to need you to request more supplies for your 'facial masks,' please." Bagged blood was junk food, but enough of it would tide him over the few more hours their plan needed. "And actually, you should take a break. Go grab lunch somewhere."

"We don't have the time to spend on me getting takeout," Tony instantly said, shaking his head.

_I can hear your heartbeat. Leave. Please._ Stephen offered a smile that was as fake as the ease in his voice. "You've been working non-stop for more than twelve hours. We're hoping to make a final push, soon. Go clear your head and we'll come back to solve the problem for good."

Tony tapped his fingers, frowned, then asked, "You sure?"

_I'm sure I want your beating heart out of here!_ "Absolutely."

"All right," Tony relented. "I'll have a courier meet me with more blood after I get something for myself, and then we'll make that final push."

As soon as Tony left the study, Stephen nearly collapsed onto the desk with relief. The damned pointy things in his mouth that had extended overnight ached with unmet need. So long as Tony sat in that study and there was nothing in the fridge, he was the only avenue for feeding Stephen's hunger. Now Stephen was alone like a wild animal kept in a zoo cage and so everyone else was safe from him. There was absolutely no way that he could get any more blood until Tony came back. Not with the sun out, and sunset wasn't for hours.

In New York.

Blinking, Stephen shook his head and tried to focus on the book in front of him. All he could think about was making that food run for Christine. Despite picking up a late lunch for them in New York, the restaurant in Spain had been nearly ready to close. 

Time zones. Of course. It was day here, but night in so many other places.

_I'm not trapped in here at all, am I?_

"Stop it," Stephen hissed at the surging, insistent logic he couldn't force away. 

Well, then. If he couldn't get rid of intrusive thoughts, he'd just get rid of this prison cell's keys.

"Tony," Stephen called as he hurried down to the first floor, where Tony was still reviewing his food options in the neighborhood. The small trash bag Stephen carried held crumpled notes, mirror shards, and at the very bottom of the pile, both sling rings that he normally kept with him. "Would you mind dumping this in a can somewhere when you head out?"

With an odd look, Tony shrugged and said, "Not sure how many cans you have around this neighborhood, but sure. Be back in a while."

There. Stephen exhaled in relief as Tony walked outside and closed the doors behind him. He was now forced to return to his study, focus on his work, and only consume the bagged blood when it eventually arrived. Patience was now key. Willpower. Human reason and logic.

_"Where in the absolute hell are you,"_ he snapped toward the empty study twenty-three minutes later.

Hunger gnawed at Stephen like a black hole, consuming everything around it: logic, focus, patience. Maybe this was a little fast to expect a courier to arrive with bagged blood, but Tony Stark was a billionaire. If anyone could make unreasonable demands and have them met, it was him. 

He wasn't going to get any work done like this. With an annoyed sigh, Stephen pushed himself up, made an impatiently reassuring gesture to the Cloak (it did not seem reassured), and walked downstairs again. He might as well simply wait for Tony here. Then he could snag a bag from him as soon as it arrived, eat his lunch, and their work could resume.

It was fortunate that the front doors had a southern exposure, Stephen thought as he stared at the painfully bright street through their inset windows. If it faced west or east, there would be hours each day when the sun streamed in to fill the room. But with windows facing south, only indirect light made it into the entry hall.

That was probably why these windows hadn't needed to go opaque like the grand one overlooking the library and artifact hall. Thanks to that, Stephen could see through them and watch impatiently for Tony's return. 

Ugh. College students were treating his front steps as a place to eat their lunch. They didn't appear to be genteel diners. They weren't going to clean up their fast food bags or cups when they left, he was sure of it.

Though he tried to ignore the students presumably taking a break from summer classes, his gaze couldn't help but wander down to a visible phone screen. With his newly keen vision, it was easy to make out messages as they were typed. The young man whose back faced the door had no clue he was being watched.

_i fucked up man. i fucked up_

Stephen's eyes narrowed.

_i didnt think she really needed her pills. she never used them!!!!!!!!!_

He was talking about a prescription medication, wasn't he? One that he'd thought was much less important than it actually was, apparently.

_but she tore some stitches and looked for the bottle but id sold it all_

That little prick. Painkillers, then. A controlled substance. Illicit possession was a felony, not that he'd probably cared.

_no but took a photo_

As the man sent that prescription label with the precise Vicodin dosage he'd stolen from his injured mother, presumably to a dealer who could help him replace the missing opioids, Stephen took a step toward the door. His own mother's suffering was nothing more than a profit opportunity?

His own thoughts screamed at him: _Stop! He's not attacking someone! He stole pills! This isn't enough!_

For a moment, his feet stopped moving. But Stephen's inhuman eyes tracked as the young man's friends stood and left, leaving him to finish his transaction on his phone.

The man's back was to the doors.

He had no idea he was being watched.

And he was on Sanctum property. Stephen could simply gesture and he'd be teleported inside. 

_Look at him,_ the newly hungry part of Stephen's mind insisted. _Benefitting from his own mother's pain. He'll do it again. You know he will. You know how many people steal pills. And he stole Vicodin. Opioids. Addictive. More people hurt. All so he can make money. He'll do it again. And soon he'll do worse. You know it. You know it._

His hand began to rise in seeming slow motion. The beast inside Stephen's body was in control and he hadn't been strong enough to fight it off. Casually sitting on the Sanctum's front steps was going to be the last thing this young man ever did.

His mother would never know why he didn't come home.

As the door opened and more light streamed in, Stephen jerked back from the sudden pain. Thoughts of elegant teleportation fled. He had to push through it. He could hear a heartbeat right in front of him. He needed this. He needed this. _I need this,_ his entire being screamed as he reached forward, grabbed the living warmth there, and pulled it into the Sanctum.

His mouth closed over sun-warmed skin as the door slammed shut. Blood erupted across his tongue. With a soft, pleased sound against the man he'd captured, he drank deeply. There was no struggle on either side. Stephen's deep satisfaction would be returned to his victim, right up until the moment his heart stopped. His hands curled around the wrist he held and—

Wrist?

Enough hot, living blood was in his system that higher thought was able to return. Blinking in confusion, Stephen looked down at where he'd been drinking: not from a neck, but from a wrist. It'd been thrust in front of him. 

"Glad I left a camera in here," panted a familiar voice. Tony must have pushed the student aside just in time. The short, shallow breaths coming out of Tony said that if he did feel any pain from this bite, pleasure overrode it. He certainly wasn't making any attempt to get away. "I saw you about to do something really dumb."

Still shocked, Stephen pulled back enough to say, "I think you just did 'really dumb.'"

"Yeah. Well." Tony swallowed, then looked down at the puncture marks in his wrist. "People tell me I'm impulsive. But I'm also real good at analyzing situations on the fly... and no way was that enough for you." For the second time, he pulled down one side of his t-shirt's collar, tilted his neck in the opposite direction, and waited. His pulse flickered.

And again.

And again.

By this point, Stephen realized as his body moved again on instinct, there was absolutely zero hope of resistance.


	6. Chapter 6

Tony didn't struggle as Stephen pulled him close. His skin was still warmed from the midday sun and a deeper, darker heat pulsed inside his veins. The faint salt of his skin tasted like summer. With a few swallows of food already inside him, Stephen was able to hold back and appreciate each sensory element with a clarity no mere human could ever have enjoyed.

Most of all, he heard the frantic pounding of Tony's heart. It had sped when his mouth descended but didn't bite. It didn't sound like fear, though. It sounded like anticipation.

"So," Tony soon gasped. He raised the arm that Stephen had bitten and used it to hold Stephen's head in place. "Gonna do it or what?"

Yes, that was probably enough waiting. Far more carefully than he'd bitten down the first time, Stephen slid into Tony as precisely as a surgical cut. A soft gasp erupted from Tony as blood exploded into Stephen's mouth. 

He could appreciate every last aspect: the taste. The heat. The source. This blood did not taste dead. Not only could he feel Tony's very life embodied within each mouthful, Stephen also tasted something that had never been inside any blood from a bag: pleasure.

Tony was enjoying the hell out of this, and Stephen knew that even before a satisfied moan erupted from him. He tasted _sweet._ The pleased noises Stephen made at the back of his throat were echoed by Tony, but that was only the start of what Tony let loose.

Desperate hands clutched Stephen's shirt and pulled him tighter. The skin under Stephen's mouth bloomed warmer as Tony flushed with arousal. "God," Tony groaned, followed by inarticulate gasps.

Stephen had halfway expected Tony to go slack in his arms, counting on inhuman strength to hold him up. Instead, Tony's arms snaked around his back and pulled them close enough that his pounding heartbeat echoed in Stephen's chest. 

A moment later, as Stephen moved one leg forward to adjust for the shift in weight, Tony ground against it. He wasn't just _blushing_ with arousal. That was clear when his erection, still locked inside his jeans, pressed against Stephen's thigh like he was trying to merge them together. "Don't stop," Tony demanded as his fists balled around the material covering Stephen's back.

Tony didn't just taste sweet, now; his blood was pure ambrosia. The pleasure he felt streamed into Stephen and filled him to his fingertips. When his hand found Tony's hair, then raked through it to lock Tony's head and neck in place, Tony let out a frantic cry of pleasure. Like the rest of his body was sent into overdrive, his hips frantically sought friction.

"Don't," Tony demanded, "stop." It came out strangled, then descended into guttural moans as he made one final, deliberate thrust against Stephen's thigh. Fists tightened, eyes closed. And in his blood, infinite pleasure and heat exploded.

Overwhelmed, Stephen drank of that pleasure deeply. When sense returned, he was relieved to hear Tony's heart still beating. It was like he'd been feeding for hours.

He pulled back, dazed at the intensity of what had just happened. The sight of blood barely trickling from twin puncture marks dizzied Stephen further. It felt like Tony's pounding pulse still echoed inside him.

Tony seemed stunned, as well. He opened his mouth, then closed it after words failed him. When their eyes met, he laughed breathlessly but looked quickly away. The color in his cheeks wasn't fading. "Right. Uh."

"Yeah." Stephen nodded.

"You will never mention this."

Stephen offered a bewildered laugh, too, and put all of his effort into not looking down the length of Tony's body. "I will never mention this."

"Okay, yeah." Tony coughed into his hand. His face was still crimson. "Where's your bathroom?"

"I'm sure you would like a bandage for your neck and wrist," Stephen obligingly said and tried to act like Tony wasn't left with anything else to _clean up._ "There are some first aid supplies in the one down that hall. Second door on your left."

"Great." Tony coughed again. "Thanks. I'll... go get a band-aid and then we can finish up."

_Oh, you already 'finished up' against my leg._ Stephen kept the smirk off his face with a heroic effort, and nodded as he watched Tony walk away with an awkward gait.

They soon wound up back in the study, but it was difficult to conduct research when neither man could bring themselves to meet the other's eyes. Still, they managed. The price of failure was too great not to prioritize. Knowing they had limited time left, their words became increasingly terse and efficient.

"Seeing better results from angular runes," Tony said as his algorithm processed its latest updates.

"Got it," Stephen said and pushed some books aside. Twenty minutes of work later, after his hands sketched out various potential runes in the air, he asked, "Any notes on these four?"

Tony's scanners might not understand this energy any better than Tony himself, but an algorithm could process huge chunks of information far faster than a human mind. That might find tiny patterns they'd overlooked. Accordingly, Tony scanned the four floating runes, waited for the system to process all the books they'd used so far, and replied, "The ones with three and six lines are probably duds like those." His hand gestured at the books that Stephen had shoved aside. It then moved to the books that still looked promising. "Five and eight lines are better chances."

"Great. Let me push some energy through them. Read them for about a minute, then make a recommendation as to which to try with a silver implementation." After establishing a dimensional energy flow through the potential runes, Stephen leaned back and waited for Tony's scanning to begin. Once it did, he said, "Thank you."

Tony still didn't look over. "We haven't found the right rune, yet. Thank me then."

"You know that's not what I meant, Tony." In the silence, Stephen continued, "The demon had taken me over. I was ready to kill that guy. You saved me from that. And you did the same thing in the park."

"Right. Well." Tony shrugged. "Then you're welcome, I guess."

"Tony." Stephen repeated his name with a smile, then raised his eyebrows. By now he did itch to bring this up and they were waiting on the algorithm. "So... I'm curious. Did you already get paid back a little for helping me?"

Gritting his teeth, Tony said nothing.

"Because it did seem like there was a bit of a 'thank you' going on."

Tony cleared his throat again.

"As you seemed to be enjoying yourself."

Though he didn't actually look over, Tony pointed at Stephen and grumbled, "This does not count as 'never mentioning it again.'"

"You seemed to be enjoying it a lot," Stephen added, then raised his eyebrows significantly.

Tony whipped around to face him. "Hey! Never mention! Never! And it says you want the five-line rune, you big prick."

Chuckling, Stephen nodded and focused back on their work. The system didn't know what this rune actually meant, only that notes about it were the best matches for what few positive indicators they had. It _did_ feel right, now that Stephen tried to manipulate the rune individually and felt the demonic infection recoil from it, but he'd need to find a creative application to put it to use. "You're right. On to the next step, then."

"How long do we have for an implementation approach?" Tony wondered as he pulled out what scarce nano supplies he still had on hand. "I. Uh." He coughed. "I'm not sure if I've got another pint to spare, yet."

Stephen smirked as he slid some less useful books out of the way. "Another couple hours, I'd guess, but I'd think you'd jump at the chance."

Tony looked ready to snap at Stephen again, if he didn't blush himself into oblivion from remembering how he'd come hard against Stephen's leg. But when Stephen trailed off in distraction, he instead frowned and asked, "You okay?"

Nodding slowly, Stephen gestured for him to wait, then re-read a page of a basic demonology text. Could it really be this simple? Had they overlooked something so straightforward about how to apply the energy flows? "I need nearly pure silver for this," he mused. "A sterling alloy should be close enough."

"Well, there's a lot of that," Tony began and looked around the study. It still held every bit of silver to be found inside the Sanctum. The Cloak leaned in, ready to grab whatever Stephen requested.

"Specifically," Stephen said, positive that he was on the right track, "I need that silver knife that you took when looking for Wong in Tikal. Do you still have it?"

"Huh? Oh, yeah, I should." Tony dug through his belongings and shortly found the knife in question. Though he moved to pass it over, hesitation stilled his hand. He stopped just short of actually giving the weapon to Stephen.

"I am in control," Stephen reassured him. "But we'll need to move quickly to keep it that way." As Tony relented and handed the knife over, Stephen continued, "I wish that I hadn't gotten rid of my sling rings, though. I'll need to have the Cloak of Levitation grab another one from Kamar-Taj—"

As Tony laid his hand against the desk with a metallic _thunk_ , Stephen looked down in confusion. The sling rings he'd tried to get Tony to dispose of were lying there when Tony's hand moved.

"When I walked out earlier," Tony explained when he saw Stephen's surprise, "I heard metal clanging at the bottom of that trash bag. After I saw what it was, I figured something was up. It's why I stayed pretty close to the door while I ate. Just in case."

"Thank you," Stephen said after a considering pause. "I really do owe you one for all of this."

"You owe me like... five," Tony laughed. "Plus Miami."

"I owe you five," Stephen gamely agreed, then gestured at the silver knife Tony had returned. The five-line rune appeared as glowing energy against its blade. Light flowed and ebbed through it, and when it faded entirely, the shape of the rune had been etched into solid metal. "There," Stephen murmured. "This knife will be perfect. Its handle has the New York protective sigil and the blade has a rune damaging to these creatures. This should work."

"Great." Tony frowned. "So, how is it going to work, exactly? You need to attack the infection everywhere, but you've only got that knife."

"We overlooked something obvious," Stephen said as he dug out his phone and tapped a contact. "Hey, yeah. Glad you were able to pick up. You're not due in surgery for at least the next... oh, ten minutes, are you? Great. I really need you to meet me in our normal spot. Yeah, sorry, it's a massive emergency."

"Dr. Christine?" Tony guessed, but was left otherwise confused. 

"You'll be there within a minute or two? Great, see you soon." Stephen hung up the call, turned to Tony, and confirmed, "Christine. It turns out we're going to need her assistance with something blood-related, after all.

"Once we go through this," Stephen continued as he slid on a ring, stowed the knife through his belt, and raised his hand, "I'll need to hurry. Carrying the sigil will help fight off the demon, but it'll still start to take me over. It's very important that you don't interrupt, particularly because a hospital has vulnerable people everywhere."

"You're positive that you know how to fight this thing?" Tony warily asked.

"I am... about eighty percent sure that—"

"Oh, great!"

"Eighty percent sure that I know exactly what to do," Stephen continued. "This should work."

"What should work?" Christine wondered as they stepped through the portal and into the hospital storage room. It had always felt a little dingy and claustrophobic when they met there to talk, but now he appreciated its complete lack of fresh air and sunlight. "Why is Mr. Stark here?"

"You've got me," Tony admitted with a shrug. "But he's apparently eighty percent sure that whatever he's about to do will work."

Christine blinked. "You have an 'eighty percent' plan? About what? Stephen, what is going on?" She blinked again. "And why are your eyes like that?"

With a deep breath, Stephen pulled the blade free. "An explanation comes later. I need to move fast." His grip tightened around the knife handle as he felt the first dangerous shadows snake through his mind. With a newly apologetic tone, Stephen added, "Christine, I really am sorry for this... but I know you can handle it."

Before either of them could stop him, he raised the knife high, felt energy flow through its dual sigils, and plunged it into his heart.

_"Holyshitwhatareyoudoing!"_ Tony demanded. Shock turned his face crimson.

Christine instead went white. "Oh God," she whimpered. "Not again."

Tony spun to face her. _"Again?!"_

Each second worsened Stephen's agony, but he never eased the energy flows pouring through the blade and into his chest. Earlier, Tony had gotten a good reaction from simultaneously attacking all blood left on the glass shard. A full body needed a different way to reach all of the blood inside it, though: attacking the organ through which all blood passed.

Vampires, after all, needed to be staked through the heart.

His immobile heart contracted to expel all of the affected blood inside it. But as soon as the Kartoth demon tried to refill his heart with blood under its control, that blood was 'vaccinated,' too. Soon Stephen's heart raced. His skin felt simply clammy against the air conditioned room instead of deathly hypothermic. As the demon inside him frantically cycled blood through his system, trying to get unprotected blood back into his heart, the blade continued its steady work. 

It hurt like hell, though.

"Is it working?" Stephen choked out. Not long had passed. It felt like hours, though.

Christine and Tony stared at him in mute horror.

"How do my eyes look?" he added, strangled. Ow. _Ow._ Okay, yes, this hurt far more than he'd anticipated.

"They're. Uh. Turning normal again," Christine managed when she realized that he actually expected a response. Behind her, Tony balanced panic and outrage in equal measures. At Tony's frantic, demanding noise a few seconds later, she added, "I mean. Yes. They're normal, now. Also _what the hell are you doing?!"_

_Oh, thank God, it worked._ Stephen's knees gave out. If not for Tony's decade of honed heroic instincts, he would have hit the floor. (And if not for Stephen's own medical instincts, he would have yanked out the searing silver agony in his chest.) "Okay. Christine. Operate now, please."

With a pained whimper, Christine lunged for a stretcher.

As he'd known would happen, Christine was able to stop his chest bleeder. For her, a simple, straightforward puncture wound from a narrow knife wasn't even a challenge.

Stephen hadn't expected quite this level of outrage from Christine and Tony when they stared at him in his medical bed afterward, though. "I can explain," he promised. His heartbeat monitor steadily beeped and a hypothermia blanket removed the last of his lingering chill.

At the pointed look Christine gave his easy tone, Stephen closed his mouth. Though they were easy to hide when he spoke in slow, measured tones, he still felt his recent fangy additions. His body temperature was resolving and the visible sign of possession on his irises was gone, but actual changes to his bone structure remained. 

(Tony probably had a great cosmetic dentist. Hopefully.)

"You are going to explain, yes," Tony levelly agreed after that short pause. "You're going to explain to her _exactly_ why you needed to do this." Christine looked at Stephen even more pointedly, but he remained silent.

"You _are going_ to explain this," Tony continued when he saw Stephen's hesitation, "because you owe me for Miami." At Stephen's disbelieving look, he added, "You've got that right, Strange. I'm calling in Miami. It's official. Tell her."

Oh, he really didn't want to share this with Christine. She already thought his new work was outlandish. But he did owe Tony for Miami... and for five more favors, by this point. "Fine," Stephen sighed. "Christine, I had to stake myself with a magical silver blade because I've been infected with vampirism for the past two days."

She said nothing, but her eyebrows inched up her forehead.

"I'm actually serious. I wish I weren't, but." He opened his mouth wide enough to showcase those damned fangs that hadn't disappeared.

At that proof, bleak acceptance overtook Christine. "Okay," she weakly agreed. "Vampires. Yeah." Then she looked up to the ceiling, sighed deeply, and whispered something that was probably an unkind assessment of life inside the New York Sanctum.

Behind her, Tony smirked. "I'll give you the card of someone who can fix those things."

"Thanks, I had my fingers crossed that you would." Though he didn't want to interrupt Christine's sighing session, Stephen did find it important to point out, "Christine, I could probably do with a blood test before I leave."

She sighed again and didn't look down. "Because of the vampire."

"Yeah."

"Oh," Tony realized. "I could use one, too."

That did make her look down with a thoughtful frown, but Christine's eyes narrowed as she surveyed Tony. Her hands caught his injured wrist and unwound its bandage. After staring in disbelief at the puncture marks there, she turned to Stephen, then back to Tony.

"He's right," Stephen agreed. "He probably needs a blood test, too."

Infinite exhaustion swept Christine. "And what exactly is under that bandage on your neck, Mr. Stark?" 

He hesitated. "Hickey."

"Does that hickey also have fang marks?"

Tony hesitated again. "'Course not."

"Sure. Whatever. I'll arrange the blood tests." Sighing, Christine turned to leave, only to pause at the door and demand one final time, "Vampires, Stephen? Really?"

"In my defense," he said around the obnoxious fangs, "I also thought this all was very stupid." 

A few long, silent seconds passed as the door closed behind Christine. "That was all incredibly foolish of you," Stephen pointed out. "I mean, I'm grateful. But looking back on everything, I can't believe you did that without any sort of backup."

"I'm as brave as I am handsome," Tony replied with a level smile.

"That's going to get you into trouble if you insist on heroics when you're supposedly retired," Stephen retorted. "Maybe you should go back to your suit, after all."

Tony's smile slid into smugness. He sat down, lounged as best he could on the uncomfortable hospital room chair, and replied, "No need. It turns out there's this pretty capable guy who'll be at my total beck and call for... hmm. Six times. Six is a good cushion."

"Six?" Stephen repeated in disbelief. "Five favors! You used up Miami."

"I'm fixing your fangs. Six favors."

"No way."

"I'm fixing the fangs _before_ you ever have to explain them to Wong." At his silence, Tony's smile somehow grew. "Six."

"I'm not at your 'beck and call,'" Stephen said after a long, useless pause. "That's way more than a favor. Beck and call is... three favors. Easily."

"We'll negotiate," Tony cheerfully retorted. "Oh. Wait. Do you not get much practice with that as a doctor? Because I might have a _tiny bit_ of practice with striking a hard bargain as, you know... former CEO of a Fortune 500 company. Current research division leader."

"Ah," Stephen said neutrally. "Striking a hard bargain. No, I wouldn't know anything about that."

Tony's eyes narrowed. "Why'd you say 'bargain' all weird? You're hiding something."

"Of course I'm not." Stephen tried to shrug, but let out a tiny, strained noise when the motion disturbed his injured chest. Tony stepped forward with a sympathetic grimace as Stephen sighed more gently and said, "Let's continue this argument later."

Tony flipped open a floating holographic calendar. "What's your release schedule?"

"Two or three days. It'd be nice if I could go straight to the dentist from here, since Wong should probably be back by then."

"You've got it." Tony added the appointment, then finished with a grin, "Is it weird that this was all kind of fun? Now that it's officially behind us?" He folded his arms and nodded in consideration. "I met an actual vampire."

"Maybe it was fun for _you,_ " Stephen began with a knowing look, "considering how you were climbing me a couple of hours ago."

Red painted Tony's cheeks. "You owe me six favors and that's final," Tony ordered as he turned to leave. Stephen's laughter followed him out.

Two days later, Stephen's tongue couldn't stop worrying at one of his re-adjusted canine teeth. "It really does feel like he left them too sharp," he grumbled as they walked through a portal and into the Sanctum's entry hall. "And I... oh, look who decided to finally rejoin us."

As he paused on the staircase at the sight of them, Wong eyed Stephen with confusion, then Tony with suspicion. He walked down the few steps to the floor and wondered, "You knew I'd be gone for the conclave. Why is Stark here?"

Ignoring that question, and the Cloak as it flew back to him, Stephen continued, "So hey, Wong! Remind me of what you said about the danger level presented by the demons of the Kartoth dimension." With a broad, fake smile, he crossed his arms over his chest and ignored the slight twinge of his stitches. "Was there anything notable to worry about?"

Wong frowned more deeply and looked between them again. "There's nothing dangerous about Kartoth, save for how quickly they breed." One eyebrow raised as he pointedly continued, "Which is why it was a risk for you to go alone."

"Really. Huh." Stephen raised an eyebrow, too. "Nothing dangerous in Kartoth. At all. There's nothing to worry about from a solitary demon getting through, then. Nothing. Not one single thing. At all."

"According to all of the books we have, yes," Wong warily agreed. Under Stephen's level stare, which was probably echoed by Tony behind him, Wong eventually cleared his throat and admitted, "I did pick up new books this week. They might have more information."

"That would be good," Stephen agreed with a thin smile.

For just a moment, the unflappable Wong seemed thoroughly confounded. But just as quickly, his typical composure returned. "Well, then. I'll look for that. As for you, Stephen... try to leave the Sanctum as less of a mess."

Yes, fine, he'd turned that room into a disaster area. Still. "It's my _private_ study." 

Wong frowned. "I meant how you left... clothes to dry in a bathroom."

Stephen blinked. "What?"

"Oh, sorry," Tony said sheepishly, then pointed toward a small hallway. "Uh. Those boxers were actually mine."

At Wong's utterly blank expression, Stephen came to the abrupt conclusion that he didn't want to explain that. At all. "Let's go grab lunch," he told Tony. "I could really go for food."

"Yes," Tony agreed, flustered. "Food. You should have _food."_

Wong squinted. "What did I miss, exactly?"

"Come on," Stephen ordered, hid the Cloak with a glamour spell, and grabbed Tony by the wrist that didn't still bear a bandage. "We're getting lunch."

"What did I miss?" Wong insisted.

"Go read your books!" Stephen insisted without looking back. "We need to fix that dimensional tear for good!" As Wong tried one last time to determine what, exactly, the two of them were refusing to tell him, Stephen opened the door. Tony needed no prompting to follow. With united purpose, they walked out of the Sanctum and into the brilliant sun.

**Notes for the Chapter:**

> I needed a few extra days to post this (got sick :( ), but thank you for following me on this extremely silly ride. And I even ended up posting on trailer day! Now, back to Bend!

**Works inspired by this one:**

  * [What We Owe To Each Other](https://archiveofourown.org/works/18483985) by [Emeraldwoman](https://archiveofourown.org/users/Emeraldwoman/pseuds/Emeraldwoman)




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